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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.nio.file;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.util.Iterator;

/**
 * An object that may be used to locate a file in a file system. It will
 * typically represent a system dependent file path.
 *
 * <p> A {@code Path} represents a path that is hierarchical and composed of a
 * sequence of directory and file name elements separated by a special separator
 * or delimiter. A <em>root component</em>, that identifies a file system
 * hierarchy, may also be present. The name element that is <em>farthest</em>
 * from the root of the directory hierarchy is the name of a file or directory.
 * The other name elements are directory names. A {@code Path} can represent a
 * root, a root and a sequence of names, or simply one or more name elements.
 * A {@code Path} is considered to be an <i>empty path</i> if it consists
 * solely of one name element that is empty. Accessing a file using an
 * <i>empty path</i> is equivalent to accessing the default directory of the
 * file system. {@code Path} defines the {@link #getFileName() getFileName},
 * {@link #getParent getParent}, {@link #getRoot getRoot}, and {@link #subpath
 * subpath} methods to access the path components or a subsequence of its name
 * elements.
 *
 * <p> In addition to accessing the components of a path, a {@code Path} also
 * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
 * resolveSibling} methods to combine paths. The {@link #relativize relativize}
 * method that can be used to construct a relative path between two paths.
 * Paths can be {@link #compareTo compared}, and tested against each other using
 * the {@link #startsWith startsWith} and {@link #endsWith endsWith} methods.
 *
 * <p> This interface extends {@link Watchable} interface so that a directory
 * located by a path can be {@link #register registered} with a {@link
 * WatchService} and entries in the directory watched. </p>
 *
 * <p> <b>WARNING:</b> This interface is only intended to be implemented by
 * those developing custom file system implementations. Methods may be added to
 * this interface in future releases. </p>
 *
 * <h2>Accessing Files</h2>
 * <p> Paths may be used with the {@link Files} class to operate on files,
 * directories, and other types of files. For example, suppose we want a {@link
 * java.io.BufferedReader} to read text from a file "{@code access.log}". The
 * file is located in a directory "{@code logs}" relative to the current working
 * directory and is UTF-8 encoded.
 * <pre>
 *     Path path = FileSystems.getDefault().getPath("logs", "access.log");
 *     BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8);
 * </pre>
 *
 * <a name="interop"></a><h2>Interoperability</h2>
 * <p> Paths associated with the default {@link
 * java.nio.file.spi.FileSystemProvider provider} are generally interoperable
 * with the {@link java.io.File java.io.File} class. Paths created by other
 * providers are unlikely to be interoperable with the abstract path names
 * represented by {@code java.io.File}. The {@link java.io.File#toPath toPath}
 * method may be used to obtain a {@code Path} from the abstract path name
 * represented by a {@code java.io.File} object. The resulting {@code Path} can
 * be used to operate on the same file as the {@code java.io.File} object. In
 * addition, the {@link #toFile toFile} method is useful to construct a {@code
 * File} from the {@code String} representation of a {@code Path}.
 *
 * <h2>Concurrency</h2>
 * <p> Implementations of this interface are immutable and safe for use by
 * multiple concurrent threads.
 *
 * @see Paths
 * @since 1.7
 */

public interface Path
    extends Comparable<Path>, Iterable<Path>, Watchable {

  /**
   * Returns the file system that created this object.
   *
   * @return the file system that created this object
   */
  FileSystem getFileSystem();

  /**
   * Tells whether or not this path is absolute.
   *
   * <p> An absolute path is complete in that it doesn't need to be combined
   * with other path information in order to locate a file.
   *
   * @return {@code true} if, and only if, this path is absolute
   */
  boolean isAbsolute();

  /**
   * Returns the root component of this path as a {@code Path} object,
   * or {@code null} if this path does not have a root component.
   *
   * @return a path representing the root component of this path, or {@code null}
   */
  Path getRoot();

  /**
   * Returns the name of the file or directory denoted by this path as a
   * {@code Path} object. The file name is the <em>farthest</em> element from
   * the root in the directory hierarchy.
   *
   * @return a path representing the name of the file or directory, or {@code null} if this path has
   * zero elements
   */
  Path getFileName();

  /**
   * Returns the <em>parent path</em>, or {@code null} if this path does not
   * have a parent.
   *
   * <p> The parent of this path object consists of this path's root
   * component, if any, and each element in the path except for the
   * <em>farthest</em> from the root in the directory hierarchy. This method
   * does not access the file system; the path or its parent may not exist.
   * Furthermore, this method does not eliminate special names such as "."
   * and ".." that may be used in some implementations. On UNIX for example,
   * the parent of "{@code /a/b/c}" is "{@code /a/b}", and the parent of
   * {@code "x/y/.}" is "{@code x/y}". This method may be used with the {@link
   * #normalize normalize} method, to eliminate redundant names, for cases where
   * <em>shell-like</em> navigation is required.
   *
   * <p> If this path has one or more elements, and no root component, then
   * this method is equivalent to evaluating the expression:
   * <blockquote><pre>
   * subpath(0,&nbsp;getNameCount()-1);
   * </pre></blockquote>
   *
   * @return a path representing the path's parent
   */
  Path getParent();

  /**
   * Returns the number of name elements in the path.
   *
   * @return the number of elements in the path, or {@code 0} if this path only represents a root
   * component
   */
  int getNameCount();

  /**
   * Returns a name element of this path as a {@code Path} object.
   *
   * <p> The {@code index} parameter is the index of the name element to return.
   * The element that is <em>closest</em> to the root in the directory hierarchy
   * has index {@code 0}. The element that is <em>farthest</em> from the root
   * has index {@link #getNameCount count}{@code -1}.
   *
   * @param index the index of the element
   * @return the name element
   * @throws IllegalArgumentException if {@code index} is negative, {@code index} is greater than or
   * equal to the number of elements, or this path has zero name elements
   */
  Path getName(int index);

  /**
   * Returns a relative {@code Path} that is a subsequence of the name
   * elements of this path.
   *
   * <p> The {@code beginIndex} and {@code endIndex} parameters specify the
   * subsequence of name elements. The name that is <em>closest</em> to the root
   * in the directory hierarchy has index {@code 0}. The name that is
   * <em>farthest</em> from the root has index {@link #getNameCount
   * count}{@code -1}. The returned {@code Path} object has the name elements
   * that begin at {@code beginIndex} and extend to the element at index {@code
   * endIndex-1}.
   *
   * @param beginIndex the index of the first element, inclusive
   * @param endIndex the index of the last element, exclusive
   * @return a new {@code Path} object that is a subsequence of the name elements in this {@code
   * Path}
   * @throws IllegalArgumentException if {@code beginIndex} is negative, or greater than or equal to
   * the number of elements. If {@code endIndex} is less than or equal to {@code beginIndex}, or
   * larger than the number of elements.
   */
  Path subpath(int beginIndex, int endIndex);

  /**
   * Tests if this path starts with the given path.
   *
   * <p> This path <em>starts</em> with the given path if this path's root
   * component <em>starts</em> with the root component of the given path,
   * and this path starts with the same name elements as the given path.
   * If the given path has more name elements than this path then {@code false}
   * is returned.
   *
   * <p> Whether or not the root component of this path starts with the root
   * component of the given path is file system specific. If this path does
   * not have a root component and the given path has a root component then
   * this path does not start with the given path.
   *
   * <p> If the given path is associated with a different {@code FileSystem}
   * to this path then {@code false} is returned.
   *
   * @param other the given path
   * @return {@code true} if this path starts with the given path; otherwise {@code false}
   */
  boolean startsWith(Path other);

  /**
   * Tests if this path starts with a {@code Path}, constructed by converting
   * the given path string, in exactly the manner specified by the {@link
   * #startsWith(Path) startsWith(Path)} method. On UNIX for example, the path
   * "{@code foo/bar}" starts with "{@code foo}" and "{@code foo/bar}". It
   * does not start with "{@code f}" or "{@code fo}".
   *
   * @param other the given path string
   * @return {@code true} if this path starts with the given path; otherwise {@code false}
   * @throws InvalidPathException If the path string cannot be converted to a Path.
   */
  boolean startsWith(String other);

  /**
   * Tests if this path ends with the given path.
   *
   * <p> If the given path has <em>N</em> elements, and no root component,
   * and this path has <em>N</em> or more elements, then this path ends with
   * the given path if the last <em>N</em> elements of each path, starting at
   * the element farthest from the root, are equal.
   *
   * <p> If the given path has a root component then this path ends with the
   * given path if the root component of this path <em>ends with</em> the root
   * component of the given path, and the corresponding elements of both paths
   * are equal. Whether or not the root component of this path ends with the
   * root component of the given path is file system specific. If this path
   * does not have a root component and the given path has a root component
   * then this path does not end with the given path.
   *
   * <p> If the given path is associated with a different {@code FileSystem}
   * to this path then {@code false} is returned.
   *
   * @param other the given path
   * @return {@code true} if this path ends with the given path; otherwise {@code false}
   */
  boolean endsWith(Path other);

  /**
   * Tests if this path ends with a {@code Path}, constructed by converting
   * the given path string, in exactly the manner specified by the {@link
   * #endsWith(Path) endsWith(Path)} method. On UNIX for example, the path
   * "{@code foo/bar}" ends with "{@code foo/bar}" and "{@code bar}". It does
   * not end with "{@code r}" or "{@code /bar}". Note that trailing separators
   * are not taken into account, and so invoking this method on the {@code
   * Path}"{@code foo/bar}" with the {@code String} "{@code bar/}" returns
   * {@code true}.
   *
   * @param other the given path string
   * @return {@code true} if this path ends with the given path; otherwise {@code false}
   * @throws InvalidPathException If the path string cannot be converted to a Path.
   */
  boolean endsWith(String other);

  /**
   * Returns a path that is this path with redundant name elements eliminated.
   *
   * <p> The precise definition of this method is implementation dependent but
   * in general it derives from this path, a path that does not contain
   * <em>redundant</em> name elements. In many file systems, the "{@code .}"
   * and "{@code ..}" are special names used to indicate the current directory
   * and parent directory. In such file systems all occurrences of "{@code .}"
   * are considered redundant. If a "{@code ..}" is preceded by a
   * non-"{@code ..}" name then both names are considered redundant (the
   * process to identify such names is repeated until it is no longer
   * applicable).
   *
   * <p> This method does not access the file system; the path may not locate
   * a file that exists. Eliminating "{@code ..}" and a preceding name from a
   * path may result in the path that locates a different file than the original
   * path. This can arise when the preceding name is a symbolic link.
   *
   * @return the resulting path or this path if it does not contain redundant name elements; an
   * empty path is returned if this path does have a root component and all name elements are
   * redundant
   * @see #getParent
   * @see #toRealPath
   */
  Path normalize();

  // -- resolution and relativization --

  /**
   * Resolve the given path against this path.
   *
   * <p> If the {@code other} parameter is an {@link #isAbsolute() absolute}
   * path then this method trivially returns {@code other}. If {@code other}
   * is an <i>empty path</i> then this method trivially returns this path.
   * Otherwise this method considers this path to be a directory and resolves
   * the given path against this path. In the simplest case, the given path
   * does not have a {@link #getRoot root} component, in which case this method
   * <em>joins</em> the given path to this path and returns a resulting path
   * that {@link #endsWith ends} with the given path. Where the given path has
   * a root component then resolution is highly implementation dependent and
   * therefore unspecified.
   *
   * @param other the path to resolve against this path
   * @return the resulting path
   * @see #relativize
   */
  Path resolve(Path other);

  /**
   * Converts a given path string to a {@code Path} and resolves it against
   * this {@code Path} in exactly the manner specified by the {@link
   * #resolve(Path) resolve} method. For example, suppose that the name
   * separator is "{@code /}" and a path represents "{@code foo/bar}", then
   * invoking this method with the path string "{@code gus}" will result in
   * the {@code Path} "{@code foo/bar/gus}".
   *
   * @param other the path string to resolve against this path
   * @return the resulting path
   * @throws InvalidPathException if the path string cannot be converted to a Path.
   * @see FileSystem#getPath
   */
  Path resolve(String other);

  /**
   * Resolves the given path against this path's {@link #getParent parent}
   * path. This is useful where a file name needs to be <i>replaced</i> with
   * another file name. For example, suppose that the name separator is
   * "{@code /}" and a path represents "{@code dir1/dir2/foo}", then invoking
   * this method with the {@code Path} "{@code bar}" will result in the {@code
   * Path} "{@code dir1/dir2/bar}". If this path does not have a parent path,
   * or {@code other} is {@link #isAbsolute() absolute}, then this method
   * returns {@code other}. If {@code other} is an empty path then this method
   * returns this path's parent, or where this path doesn't have a parent, the
   * empty path.
   *
   * @param other the path to resolve against this path's parent
   * @return the resulting path
   * @see #resolve(Path)
   */
  Path resolveSibling(Path other);

  /**
   * Converts a given path string to a {@code Path} and resolves it against
   * this path's {@link #getParent parent} path in exactly the manner
   * specified by the {@link #resolveSibling(Path) resolveSibling} method.
   *
   * @param other the path string to resolve against this path's parent
   * @return the resulting path
   * @throws InvalidPathException if the path string cannot be converted to a Path.
   * @see FileSystem#getPath
   */
  Path resolveSibling(String other);

  /**
   * Constructs a relative path between this path and a given path.
   *
   * <p> Relativization is the inverse of {@link #resolve(Path) resolution}. This method attempts to
   * construct a {@link #isAbsolute relative} path that when {@link #resolve(Path) resolved} against
   * this path, yields a path that locates the same file as the given path. For example, on UNIX, if
   * this path is {@code "/a/b"} and the given path is {@code "/a/b/c/d"} then the resulting
   * relative path would be {@code "c/d"}. Where this path and the given path do not have a {@link
   * #getRoot root} component, then a relative path can be constructed. A relative path cannot be
   * constructed if only one of the paths have a root component. Where both paths have a root
   * component then it is implementation dependent if a relative path can be constructed. If this
   * path and the given path are {@link #equals equal} then an <i>empty path</i> is returned.
   *
   * <p> For any two {@link #normalize normalized} paths <i>p</i> and <i>q</i>, where <i>q</i> does
   * not have a root component, <blockquote> <i>p</i><tt>.relativize(</tt><i>p</i><tt>.resolve(</tt><i>q</i><tt>)).equals(</tt><i>q</i><tt>)</tt>
   * </blockquote>
   *
   * <p> When symbolic links are supported, then whether the resulting path, when resolved against
   * this path, yields a path that can be used to locate the {@link Files#isSameFile same} file as
   * {@code other} is implementation dependent. For example, if this path is  {@code "/a/b"} and the
   * given path is {@code "/a/x"} then the resulting relative path may be {@code "../x"}. If {@code
   * "b"} is a symbolic link then is implementation dependent if {@code "a/b/../x"} would locate the
   * same file as {@code "/a/x"}.
   *
   * @param other the path to relativize against this path
   * @return the resulting relative path, or an empty path if both paths are equal
   * @throws IllegalArgumentException if {@code other} is not a {@code Path} that can be relativized
   * against this path
   */
  Path relativize(Path other);

  /**
   * Returns a URI to represent this path.
   *
   * <p> This method constructs an absolute {@link URI} with a {@link
   * URI#getScheme() scheme} equal to the URI scheme that identifies the
   * provider. The exact form of the scheme specific part is highly provider
   * dependent.
   *
   * <p> In the case of the default provider, the URI is hierarchical with
   * a {@link URI#getPath() path} component that is absolute. The query and
   * fragment components are undefined. Whether the authority component is
   * defined or not is implementation dependent. There is no guarantee that
   * the {@code URI} may be used to construct a {@link java.io.File java.io.File}.
   * In particular, if this path represents a Universal Naming Convention (UNC)
   * path, then the UNC server name may be encoded in the authority component
   * of the resulting URI. In the case of the default provider, and the file
   * exists, and it can be determined that the file is a directory, then the
   * resulting {@code URI} will end with a slash.
   *
   * <p> The default provider provides a similar <em>round-trip</em> guarantee
   * to the {@link java.io.File} class. For a given {@code Path} <i>p</i> it
   * is guaranteed that
   * <blockquote><tt>
   * {@link Paths#get(URI) Paths.get}(</tt><i>p</i><tt>.toUri()).equals(</tt><i>p</i>
   * <tt>.{@link #toAbsolutePath() toAbsolutePath}())</tt>
   * </blockquote>
   * so long as the original {@code Path}, the {@code URI}, and the new {@code
   * Path} are all created in (possibly different invocations of) the same
   * Java virtual machine. Whether other providers make any guarantees is
   * provider specific and therefore unspecified.
   *
   * <p> When a file system is constructed to access the contents of a file
   * as a file system then it is highly implementation specific if the returned
   * URI represents the given path in the file system or it represents a
   * <em>compound</em> URI that encodes the URI of the enclosing file system.
   * A format for compound URIs is not defined in this release; such a scheme
   * may be added in a future release.
   *
   * @return the URI representing this path
   * @throws java.io.IOError if an I/O error occurs obtaining the absolute path, or where a file
   * system is constructed to access the contents of a file as a file system, and the URI of the
   * enclosing file system cannot be obtained
   * @throws SecurityException In the case of the default provider, and a security manager is
   * installed, the {@link #toAbsolutePath toAbsolutePath} method throws a security exception.
   */
  URI toUri();

  /**
   * Returns a {@code Path} object representing the absolute path of this
   * path.
   *
   * <p> If this path is already {@link Path#isAbsolute absolute} then this
   * method simply returns this path. Otherwise, this method resolves the path
   * in an implementation dependent manner, typically by resolving the path
   * against a file system default directory. Depending on the implementation,
   * this method may throw an I/O error if the file system is not accessible.
   *
   * @return a {@code Path} object representing the absolute path
   * @throws java.io.IOError if an I/O error occurs
   * @throws SecurityException In the case of the default provider, a security manager is installed,
   * and this path is not absolute, then the security manager's {@link
   * SecurityManager#checkPropertyAccess(String) checkPropertyAccess} method is invoked to check
   * access to the system property {@code user.dir}
   */
  Path toAbsolutePath();

  /**
   * Returns the <em>real</em> path of an existing file.
   *
   * <p> The precise definition of this method is implementation dependent but
   * in general it derives from this path, an {@link #isAbsolute absolute}
   * path that locates the {@link Files#isSameFile same} file as this path, but
   * with name elements that represent the actual name of the directories
   * and the file. For example, where filename comparisons on a file system
   * are case insensitive then the name elements represent the names in their
   * actual case. Additionally, the resulting path has redundant name
   * elements removed.
   *
   * <p> If this path is relative then its absolute path is first obtained,
   * as if by invoking the {@link #toAbsolutePath toAbsolutePath} method.
   *
   * <p> The {@code options} array may be used to indicate how symbolic links
   * are handled. By default, symbolic links are resolved to their final
   * target. If the option {@link LinkOption#NOFOLLOW_LINKS NOFOLLOW_LINKS} is
   * present then this method does not resolve symbolic links.
   *
   * Some implementations allow special names such as "{@code ..}" to refer to
   * the parent directory. When deriving the <em>real path</em>, and a
   * "{@code ..}" (or equivalent) is preceded by a non-"{@code ..}" name then
   * an implementation will typically cause both names to be removed. When
   * not resolving symbolic links and the preceding name is a symbolic link
   * then the names are only removed if it guaranteed that the resulting path
   * will locate the same file as this path.
   *
   * @param options options indicating how symbolic links are handled
   * @return an absolute path represent the <em>real</em> path of the file located by this object
   * @throws IOException if the file does not exist or an I/O error occurs
   * @throws SecurityException In the case of the default provider, and a security manager is
   * installed, its {@link SecurityManager#checkRead(String) checkRead} method is invoked to check
   * read access to the file, and where this path is not absolute, its {@link
   * SecurityManager#checkPropertyAccess(String) checkPropertyAccess} method is invoked to check
   * access to the system property {@code user.dir}
   */
  Path toRealPath(LinkOption... options) throws IOException;

  /**
   * Returns a {@link File} object representing this path. Where this {@code
   * Path} is associated with the default provider, then this method is
   * equivalent to returning a {@code File} object constructed with the
   * {@code String} representation of this path.
   *
   * <p> If this path was created by invoking the {@code File} {@link
   * File#toPath toPath} method then there is no guarantee that the {@code
   * File} object returned by this method is {@link #equals equal} to the
   * original {@code File}.
   *
   * @return a {@code File} object representing this path
   * @throws UnsupportedOperationException if this {@code Path} is not associated with the default
   * provider
   */
  File toFile();

  // -- watchable --

  /**
   * Registers the file located by this path with a watch service.
   *
   * <p> In this release, this path locates a directory that exists. The
   * directory is registered with the watch service so that entries in the
   * directory can be watched. The {@code events} parameter is the events to
   * register and may contain the following events:
   * <ul>
   * <li>{@link StandardWatchEventKinds#ENTRY_CREATE ENTRY_CREATE} -
   * entry created or moved into the directory</li>
   * <li>{@link StandardWatchEventKinds#ENTRY_DELETE ENTRY_DELETE} -
   * entry deleted or moved out of the directory</li>
   * <li>{@link StandardWatchEventKinds#ENTRY_MODIFY ENTRY_MODIFY} -
   * entry in directory was modified</li>
   * </ul>
   *
   * <p> The {@link WatchEvent#context context} for these events is the
   * relative path between the directory located by this path, and the path
   * that locates the directory entry that is created, deleted, or modified.
   *
   * <p> The set of events may include additional implementation specific
   * event that are not defined by the enum {@link StandardWatchEventKinds}
   *
   * <p> The {@code modifiers} parameter specifies <em>modifiers</em> that
   * qualify how the directory is registered. This release does not define any
   * <em>standard</em> modifiers. It may contain implementation specific
   * modifiers.
   *
   * <p> Where a file is registered with a watch service by means of a symbolic
   * link then it is implementation specific if the watch continues to depend
   * on the existence of the symbolic link after it is registered.
   *
   * @param watcher the watch service to which this object is to be registered
   * @param events the events for which this object should be registered
   * @param modifiers the modifiers, if any, that modify how the object is registered
   * @return a key representing the registration of this object with the given watch service
   * @throws UnsupportedOperationException if unsupported events or modifiers are specified
   * @throws IllegalArgumentException if an invalid combination of events or modifiers is specified
   * @throws ClosedWatchServiceException if the watch service is closed
   * @throws NotDirectoryException if the file is registered to watch the entries in a directory and
   * the file is not a directory  <i>(optional specific exception)</i>
   * @throws IOException if an I/O error occurs
   * @throws SecurityException In the case of the default provider, and a security manager is
   * installed, the {@link SecurityManager#checkRead(String) checkRead} method is invoked to check
   * read access to the file.
   */
  @Override
  WatchKey register(WatchService watcher,
      WatchEvent.Kind<?>[] events,
      WatchEvent.Modifier... modifiers)
      throws IOException;

  /**
   * Registers the file located by this path with a watch service.
   *
   * <p> An invocation of this method behaves in exactly the same way as the invocation
   * <pre>
   *     watchable.{@link #register(WatchService, WatchEvent.Kind[], WatchEvent.Modifier[])
   * register}(watcher, events, new WatchEvent.Modifier[0]);
   * </pre>
   *
   * <p> <b>Usage Example:</b> Suppose we wish to register a directory for entry create, delete, and
   * modify events:
   * <pre>
   *     Path dir = ...
   *     WatchService watcher = ...
   *
   *     WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
   * </pre>
   *
   * @param watcher The watch service to which this object is to be registered
   * @param events The events for which this object should be registered
   * @return A key representing the registration of this object with the given watch service
   * @throws UnsupportedOperationException If unsupported events are specified
   * @throws IllegalArgumentException If an invalid combination of events is specified
   * @throws ClosedWatchServiceException If the watch service is closed
   * @throws NotDirectoryException If the file is registered to watch the entries in a directory and
   * the file is not a directory  <i>(optional specific exception)</i>
   * @throws IOException If an I/O error occurs
   * @throws SecurityException In the case of the default provider, and a security manager is
   * installed, the {@link SecurityManager#checkRead(String) checkRead} method is invoked to check
   * read access to the file.
   */
  @Override
  WatchKey register(WatchService watcher,
      WatchEvent.Kind<?>... events)
      throws IOException;

  // -- Iterable --

  /**
   * Returns an iterator over the name elements of this path.
   *
   * <p> The first element returned by the iterator represents the name
   * element that is closest to the root in the directory hierarchy, the
   * second element is the next closest, and so on. The last element returned
   * is the name of the file or directory denoted by this path. The {@link
   * #getRoot root} component, if present, is not returned by the iterator.
   *
   * @return an iterator over the name elements of this path.
   */
  @Override
  Iterator<Path> iterator();

  // -- compareTo/equals/hashCode --

  /**
   * Compares two abstract paths lexicographically. The ordering defined by
   * this method is provider specific, and in the case of the default
   * provider, platform specific. This method does not access the file system
   * and neither file is required to exist.
   *
   * <p> This method may not be used to compare paths that are associated
   * with different file system providers.
   *
   * @param other the path compared to this path.
   * @return zero if the argument is {@link #equals equal} to this path, a value less than zero if
   * this path is lexicographically less than the argument, or a value greater than zero if this
   * path is lexicographically greater than the argument
   * @throws ClassCastException if the paths are associated with different providers
   */
  @Override
  int compareTo(Path other);

  /**
   * Tests this path for equality with the given object.
   *
   * <p> If the given object is not a Path, or is a Path associated with a
   * different {@code FileSystem}, then this method returns {@code false}.
   *
   * <p> Whether or not two path are equal depends on the file system
   * implementation. In some cases the paths are compared without regard
   * to case, and others are case sensitive. This method does not access the
   * file system and the file is not required to exist. Where required, the
   * {@link Files#isSameFile isSameFile} method may be used to check if two
   * paths locate the same file.
   *
   * <p> This method satisfies the general contract of the {@link
   * java.lang.Object#equals(Object) Object.equals} method. </p>
   *
   * @param other the object to which this object is to be compared
   * @return {@code true} if, and only if, the given object is a {@code Path} that is identical to
   * this {@code Path}
   */
  boolean equals(Object other);

  /**
   * Computes a hash code for this path.
   *
   * <p> The hash code is based upon the components of the path, and
   * satisfies the general contract of the {@link Object#hashCode
   * Object.hashCode} method.
   *
   * @return the hash-code value for this path
   */
  int hashCode();

  /**
   * Returns the string representation of this path.
   *
   * <p> If this path was created by converting a path string using the
   * {@link FileSystem#getPath getPath} method then the path string returned
   * by this method may differ from the original String used to create the path.
   *
   * <p> The returned path string uses the default name {@link
   * FileSystem#getSeparator separator} to separate names in the path.
   *
   * @return the string representation of this path
   */
  String toString();
}
